Highway crossing signal



Dec. 1,1931.

A. J. SORENSEN 3 ,834,0 HIGHWAY CROSSING SIGNAL Filed July 50. 1930 INVENTOR 1 NQ ATTORNEY Patented Dec. 1, 1931 UNITED STATES PATENT... OFFICE.

ANDREW J. SORENSEN,

{PENNSYLVANIA or PITTSBURGH, PElINSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, or swIssv LE, PENNSYLVANIA, A conroa TIoN or I HIGHWAY CROSSING .sIGNAI.

Application filed July 30, 1980. Serial-No. 471,681.

relates to highway crossing signals located at intersections of railways and highways, to warn users of the highway when a train approaches the crossing along the railway.

I will describe two forms of highway crossing signals embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a top plan view showing an intersection of a highway and a railway provided with a highway crossing signal embodying my invention. Fig. 2 is a sectional view, showing a portion of the apparatus illustrated in Fig. 1, and also embodying my invention.

Fig. 3 is a view similar to Fig. 2, showing a modified form of a portion of the apparatus illustrated in Fig. 1.

Similar reference characters refer to similar parts in all three views.

Referring to the drawings, the reference characters 1 and 1 designate the track rails of a stretch of railway track, which rails are supported by the usual crossties T. This stretch of railway track intersects a highway My invention signals, that Is,

indicated diagrammatically at H.

' trodes E and E 7 distance from the Located adjacent the crossing of the railway and the highway, is a crossing signal 0 any usual and well known form, here illustrated as an electric bell. The signal S is supplied with energy from a source of current, which, as here shown, is a battery 8, over back contact 2 of a control relay R and circuit wires 11 and 12. The relay R is controlled by a microphone device M attached to a track rail and located an appropriate 7 crossing.

As best seen in Fig. 2, the device M is attached to the rail 1 by means of a clamp 4 which is secured to the flange of the rail by a lug 5, and a bolt 15. In the form here shown, the device M comprises a microphone having an insulating housing 14 attached to the clamp i by a screw 16, and containing two spaced vertically disposed metal elec- The space between the electrodes E and E is partly but not Wholly filled with loose carbon globules 13. Current from a suitable source such as a battery 7 is supplied to relay B through the device Mand a resistance 3, as best seen in Fig. 1. The mounting of the microphone may be carried out in a variety of ways, provided the position shown in Fig. 2- is used. Since the microphone has been found to be sensitive to'both vertical and horizontal shocks, it may be mounted in the way shown 'in Fig. 3 in which it will receive a combination of both. As shown in this view, the microphone is fastened to an angle member 17 by screw 16, and the said angle member 17 is pivotally mounted at 9 in a support not shown in the drawings. A spring W is held in place by a clamp 19 fixed by a bolt 18 to an angle plate 10 located in the trackway. The angle member 17 is normally held in engagement with the flange ofrail 1 by virtue of compression in springWV.

The operation of the apparatus is as follows: WVith the microphone in proper adjustment, enough current will flow through it under normal conditions, to energize relay R and hold contact 2 open, thereby preventing operation of the signal S. Then a train, approaching highway dicated by the arrow, is passing device M, the vibration of the track rail 1*? caused by the f train, is transmitted to device M, by means vibrated until the train has passed beyond device. M for some distance. While device M is being vibrated, the carbon globules 13 within the device are continually agitated, and the resistance of the current path between the electrodes E and E of device M varies rapidly, being at times below its normal value and at other times above this value. The average value of the resistance is of the order of two or three times the normal value, but the peak value rises'to about ten times normal value, and thismakes it possible to obtain, by using a quick-acting relay, a wide margin of operation. The increase in the resistance of the microphone reduces the current flow through the relay R, and the relay becomes deenergized. The consequent closing of back contact 2 of relay R completes the circuit for signal S, thereby H in the direction inappended claims without phone attached to said operating the signal and warning users of the highway of the approach of a train along the railwa A microphone of the type described varies its resistance in accordance with the firm ness of the contact between the carbon glob ules and between the globules and themetal electrodes.

creases as the path resistance decreases, and

therefore, whenpoor contact is made between the carbon globules due to the vibrations caused by a passing train, the resistance of the microphone increases. bodying my invention therefore operates on the normally energizedprinciple, so that any failure in the operating circuit for relay R, or any defect in the device M will result in d-eenergization of relay R and the consequent operation of signal S.

Although I have herein shown and. described only two forms ofhighway crossing signals embodying inyinvention, itis under-- stood that various changes and modifications may be madetherein within the scope of the departing from scope of my invention. described my invention, what the spirit and Having thus I claim is:

track rail, a microrail and having the characteristic of increasing its resistance when the rail is vibrated by the passage of a: train, a circuit including said microphone and a relay as well as a source of current, whereby the relay is normally energized but becomes deenergized when said rail is Vibrated by the passage of a train, and a highway crossing signal controlled by said relay.

2. In combination, a track rail, an angle member pivotally supported in the track- Way, a spring urging said angle member into. engagement with said rail, an insulating housing attachedto said angle member, and a microphone in said housing which has the characteristic of increasing its" resistance 1 In combination, a

when the rail is vibrated by the passage of a train. V

In testimony whereof I afiix my signature. ANDREW J. SORENSEN.

It is known that current flow in- Apparatus ern- 

